The present invention relates to a closure for a fuel tank filler neck, including a closure cap swivel-mounted on an upper side of the closure and openable from a closed position by a force acting on a lever arm arranged at a remote side of the swivel axis.
German Patent No. Specification 4,217,966 discloses a closure with a closure cap having at its swivel axis a closing spring prestressed in the closing direction. Upon the swivelling back of the closure cap into the closed position, the cap presses the pawl to the side in order to engage therebehind. If, however, over a period of time, the closing spring shows signs of fatigue and/or dirt particles enter into the swivel mounting of the closure cap, a secure closure of the filler neck is no longer provided, because the closing force of the spring is then not adequate to accomplish a sealed bearing contact of the cap against the passage opening. In that case, the closing force may be so minimal that not even the pawl is overcome, meaning that the cap rests on the pawl. As a result, fuel in a gaseous and liquid state can escape from the tank, which leads to the vehicle and other road users being put at risk and to the environment being polluted.
An object of the present invention is to provide a closure such that a permanent and reliable closing function of the closure cap is ensured. This object has been achieved according to the present invention in the following ways. According to a first embodiment, an axially accessible adjusting ring, is arranged coaxially with respect to the filler neck and is at least one of mounted rotatably on an outer circumference of the filler neck and on an axial end face of a shoulder of the filler neck. The ring has on its upper side, at least in a subregion thereof, spiral toothing, and the lever arm on the closure cap has a toothed segment with teeth configured and arranged to engage with the spiral toothing of the ring such that a turning of the adjusting ring exerts the force for opening and closing the closure cap. According to a second embodiment, the swivel axis is arranged parallel to an axis of the filler neck. A driving element is arranged in proximity to the swivel axis, outside a clear cross-section of the passage, for effecting a swivelling movement of the closure cap, and an adjusting ring is one of mounted concentrically with respect to the filler neck and able to be inserted therein in a centered manner, via a corresponding mating form-fit element connected with a form fit to the driving element, for initiating the swivelling movement of the closure cap.
Because of the positive drive of the closure cap, acting both in the opening direction and in the closing direction, the force exerted on the swivelling of the closure cap can, in all events, exceed a resistance opposing the swivelling movement, which resistance may be caused, for example, by dirt particles lodged in the mechanism. This means that any swivel position can nevertheless be adopted. Moreover, it is possible to dispense with the arrangement of a closing spring, which prevents a fatigue-induced reduction in closing force from occurring. Altogether, consequently a permanent and reliable closing function of the closure cap is achieved by the invention.